This invention relates to sewerage systems, and more specifically to a remotely controlled, gas sensing sewerage pipe vehicle for inspection or repair of sewerage pipes.
Modem sewerage systems are often inspected for breaks, cracks, spalling of pipe, poor joints, and other defects by using waterproof video equipment mounted on a mechanical device which can be remotely operated while it crawls along sewerage pipes, or Is towed on a skid or skate. Of course, it has been long recognized, that organic matter is undergoing decomposition within the confined spaces such as found within a sewerage system. Decomposition of organic matter may proceed with the generation of various gases, some of which may be toxic to humans, and some of which may be explosive when in sufficient concentration. Human toxicity of these gases may be aggravated by the low oxygen concentration expected in the sewerage system. Often, before entering a manhole, personnel must wait until the space has been ventilated mechanically for a period of time, and must then test the area for gases. Partly for this reason it is typically required that at least two people work together when entering a sewerage system, and that those entering wear a safety harness.
Additionally, there is some concern in the industry that the concentration of certain gases may rise sufficiently within the sewerage system to produce an explosive mixture. This concern relates to pipe crawler devices which may generate a gas igniting spark through their electrical or mechanical components. Because of industry concern, the possible establishment of standards is being explored to require that remotely controlled pipe crawlers be fabricated incorporating xe2x80x9cexplosion proofxe2x80x9d technology, which is intended to substantially reduce or eliminate the risk of spark generation by the device. Such explosion proof equipment will be more difficult to manufacture, and consequently will be more expensive.
With the foregoing in mind, the present invention provides an alternative approach addressing industry concern over potential explosions or toxic levels of gas found during sewerage pipe inspections. The invention comprises a pipe vehicle which includes a gas sensor for detecting a predetermined level of potentially explosive gas. Responsive to the sensor, an alarm could be generated, or power to the vehicle could be interrupted before the level of gas rises sufficiently above a danger level, for example for flammability or for sustaining an explosion. The skilled should recognize that the invention is intended to include any other pipe vehicle device useful for inspection, maintenance, and repair of sewerage pipes, including for example cameras, cutters, packers and other grouting equipment, and the like. These devices are referred to herein collectively by the generic designation xe2x80x9cpipe vehicle.xe2x80x9d